The invention relates to a lubrication pump and a method of producing the lubrication pump, and more particularly to a lubrication pump for a vehicle transfer case which pumps a lubricant through a passageway in an axial bore of a shaft.
A four wheel drive vehicle includes a vehicle transfer case for distributing a driving force from a transmission connected to a prime mover such as an internal combustion engine to front and rear wheels through a vehicle drive train assembly. The transfer case is adapted to be secured to one end of the vehicle transmission. An input shaft is rotatably supported within the transfer case for coupling with an output shaft of the vehicle transmission. The input shaft of the transfer case is coupled to a speed change mechanism which is then coupled to an output shaft of the transfer case. The output shaft of the transfer case is then coupled with the vehicle drive train assembly. Lubrication of a plurality of bearings within the transfer case is accomplished by a pumping mechanism, such as a gerotor pump, which is mounted on the input shaft of the transfer case and pumps a lubricant through an axial bore of the input shaft.
Typically, pumping mechanisms have been constructed of cast aluminum which has been precision machined. Restriction of the total weight, durability, and temperature resistance of materials used to produce the pumps are a concern for design of the pumping mechanism.
It would be desirable to produce a lubrication pump for a vehicle transfer case in which weight is minimized and durability and temperature resistance are maximized.
Consistent and consonant with the present invention, a lubrication pump for a vehicle transfer case in which weight is minimized and durability and temperature resistance are maximized has surprisingly been discovered. The lubrication pump for a vehicle transfer case comprises:
a pump body having a generally hollow cylindrical shape and a central longitudinal axis, one end of the pump body having a radial wall with a centrally disposed aperture;
a synthetic polymer pump insert having a generally cylindrical main body with a central aperture, an inlet channel, and an outlet channel, the inlet channel in fluid communication with a source of lubricating fluid and the outlet channel in fluid communication with the central aperture of the main body, the pump insert inserted in the pump body;
a synthetic polymer outer gear, the outer gear being generally ring shaped with an inner surface forming an aperture, the inner surface having a generally sinusoidal shape which forms a plurality of peaks and valleys, the outer gear received in the pump body adjacent the pump insert;
a synthetic polymer inner gear, the inner gear being generally disc shaped with a central aperture formed by an inner surface, the inner surface having a shaft engaging portion to drivingly engage the inner gear with a shaft of a vehicle transfer case, an outer surface of the inner gear having a generally sinusoidal shape which forms a plurality of peaks and valleys, the number of peaks and valleys of the outer surface of the inner gear being at least one less than the number of peaks and valleys of the inner surface of the outer gear, the inner gear rotatingly received in the central aperture of the outer gear adjacent the pump insert; and
a generally disc shaped pump cover having a central aperture, the pump cover attached to the pump body to enclose the pump insert, the outer gear and the inner gear within the pump body and form a substantially liquid tight seal with the pump body.